AV-Test
Although most search engines have measures in place to protect users against trojans, malicious sites still manage to crop up from time to time -- even in the top search results. An independent testing lab in Germany by the name of AV-Test has just completed an 18-month survey to find out which search engines are the worst offenders.

The lab tested 40 million Web sites (PDF) across seven search engines -- Google and Bing, the world's two most popular search engines; Yandex, Russia's biggest search engine; Blekko; peer-to-peer search engine Faroo; Teoma, better known as Ask.com; and Chinese search engine Baidu -- and found only a very small number of malicious results returned: about 5,000, or around 0.000125 percent.

Google and Bing were both tested with around 10 million Web sites, and were the best at weeding out malware. However, it should be noted that there was quite a gap between the two: Bing turned up 1,285 malicious sites to Google's 272.